Does anyone have a simple explanation of the wiring layout on a 79 F250 v8? Mine has the posts on the side I believe rather than the back. My dads also has a 400 and his has the posts on the back. The one wire on mine is melted and ripped off, I have no clue what it is for but it seems to charge. The lights pulse a lot and I think that may be the regulator or possibly the wiring going to it. Like some of the others it too is not in the best shape.

I tried a quick advanced search and so much is related to alt swaps.

 

The OE alternator on my '78/400 also had rear terminals. I have linked a picture of a Ford 1G case style Powermaster for reference. If you click "360 view" you can see the connections which look same as on my OE alternator.

The big one is the charge wire and the smaller wires to energize and regulate the alternator. From memory, terminal stud size in the smaller wires is different.

I'm not an expert but don't know of any OE 1g alternators with side terminals. Maybe it is a super heavy duty option or swapped.

Can you see an amp rating? Common OE would have been 60 or 65 amp max. My example was rated 40 amps.

Powermaster Street Alternators 17078 - Free Shipping on Orders Over $99 at Summit Racing

 

Maybe this will help?

 

My 79 f350 had the side terminal and it has the 351m. The truck was originally a sandwich truck and I assumed it was due to the extra amperage needs that it had a different alternator. Truck has been parted but still have the motor in one unit and can get pics of alternator and wiring harness for that area.
highjack
My 75 f250 390 auto has had an overcharging problem since I got it and no matter what I do it wont go away, yet everything is working right according to digital ammeter. No damage to wiring, multiple voltage regulators tested, grounded to frame, have tried 2 alternators and 2 solenoids. All parts used were tested and are working properly.

 

First question about original alernator wiring, is do you have an ammeter gauge?

The ammeter add a pile of wiring that complicates things, while the alternator light cluster is much simpler.

 

I do have a gauge and it does work. That red wire in my hand looks like it got very hot at some point. Even the main harness below isn't in that good of shape. Something needs to be done it will drive me nuts at night time.

 

i see you have the 90 amp alt,just replace that wire

 

I figured it did have a higher output alt since this was a snowplow package truck. My question still is where exactly does it go and what does it do? Looking at the diagram I'm still not sure. It must not do much because it still charges.

 

Even though it's not done and I still have plenty to do i had to take a road trip. Today was the first day it's finally legal to drive (or at least most of the way).
June


Tonight

 

Hmmm, pretty sure I saw a engine harness up in the barn the other night...let me know if yours gets too ugly.

I see the case...well....any luck? they are chasing hot and heavy in my neck of the woods.

 

Hard to tell from the pic... is the alternator terminal the red wire attaches to insulated? Or is it just a case ground?

 

You have the large case Motorcraft alternator w/ 70 amp output.
The harness you need is D9TZ-14305-B Thats for a '79 F100-350 w/ 70 amp alternator and ammeter and oil pressure gauge. Unfortunately no dealer or obsolete parts supplier shows having one in stock.

 

Actually I did have some luck tonight. I'll post it if you guys want to see a decent 8 pt. I'm not sure if it will offend anyone.

Do you think you have the harness Mike is talking about? Mine is bad several places. If I have to I can probably make a new one or something but I'm open to options.

 

Thanks. I wonder if the 70a is much of a improvement over the normal one.

 

Heck yea, show the pics or 8 pt didnt happen!!!

I wont be able to see if it has the right connectors till Sunday...I'll track you down then. Actually I have quite a few so hopefully there is something there.